The present invention relates in general to development stations for reproduction apparatus, and more particularly to a cleaning mechanism including a polyurethane blade cleaner for the toning roller of a development station of an electrostatographic reproduction apparatus.
In reproduction apparatus, such as electrostatographic copiers or printers for example, it is general practice to apply a uniform electrostatic charge to a dielectric member and modify such charge to form a latent charge pattern corresponding in image-wise fashion to information to be reproduced. The latent image charge pattern is then developed by applying pigmented marking particles to the dielectric member. The particles, which are charged to a polarity opposite to that of the latent image charge pattern on the dielectric member or to a substantially different charge level, adhere to the pattern to form a developed image on the dielectric member. The developed image is then fixed to the dielectric member, or transferred to a final receiver member and fixed thereto by heat and/or pressure for example.
One type of development station commonly utilized in electrostatographic reproduction apparatus is the magnetic brush development station. The magnetic brush development station includes a housing providing a reservoir for a supply of developer material. The developer material may be, for example, two-component material comprising magnetic carrier particles and relatively smaller pigmented marking particles. A mechanism, such as a paddle wheel, auger or ribbon blender, is located in the reservoir and serves to stir the carrier particles and marking particles to triboelectrically charge the particles so that the marking particles adhere to the surface of the carrier particles. A transport mechanism brings the developer material into the field of a plurality of magnets within a rotating sleeve (commonly referred to as the toning roller). The rotating sleeve and magnetic fields cause the marking particles to be brought into the vicinity of the latent image charge patterns on the dielectric member to be applied to the latent image charge patterns in order to develop such patterns.
Under certain conditions a fine coating of marking particles (commonly referred to as scum) tends to build up on the toning roller of the magnetic brush development station. Such scum leads to unacceptable degradation of image quality through incomplete development of the latent image charge pattern on the dielectric member. In order to prevent rapid build up of marking particle scum, active cleaner hardware is provided in association with the development station toning roller. See for example U.S. Pat. No. 4,999,675 (issued Mar. 12, 1991, in the names of Speer et al), and U.S. Pat. No. 5,143,017 (issued Sep. 1, 1992, in the names of Haneda et al). Active cleaner hardware, such as that shown in the above mentioned patents, typically includes a skive blade urged into contact with the toning roller of the development station. Known skive blades have been found to be subject to high wear. Such high wear causes heat to be generated of sufficient magnitude to produce undesirable marking particle flakes or agglomerates. Flakes and agglomerates add to image quality degradation by causing objectionable artifacts in the developed images. Also, the skive pressure on the toning roller can result in excessive torque on the drive for the toning roller. This, in turn, leads to a decrease in part life (reliability) and an increase in service costs.